1. Field of the Invention
The present invention relates to a heat emitting probe that performs thermal operations in a pinpoint fashion on the surface of a sample and to an apparatus that uses such a heat emitting probe.
2. Prior Art
Conventionally, magnetic recording media such as magnetic disks, etc., and optical recording media such as optical disks, etc. are widely used as recording media for information. In recent years, thermal recording media have begun to be developed.
Such thermal recording media are obtained from a low-melting-point organic substance, and information is recorded on such media by forming fusion type holes in the surface thereof by means of heat. For example, a hole is defined as “1”, and the absence of a hole is defined as “0”; and information is recorded by series of these holes. Since the density at which information is recorded increases with a decrease in the diameter of these holes (hereafter referred to as the “hole diameter”), the size of a heat emitting probe used for heating is important.
FIG. 9 is a schematic perspective view showing the manner of recording of information by way of a conventional heat emitting probe.
This heat emitting probe 19 is constructed by machining an AFM cantilever 2 that is used in an atomic force microscope (AFM). The cantilever 2 comprises a cantilever portion 4 and a holder 8 that is disposed so as to protrude from the tip end of the cantilever portion 4. In an AFM cantilever, the holder 8 is usually called a protruding portion or pyramid portion.
Electrode films 5 and 6 are provided on both side surfaces of the cantilever portion 4. These films are formed by coating the side surfaces of the cantilever portion 4 with a conductive substance. A control circuit C is connected to the rear ends of the electrode films 5 and 6 via contact points 5a and 6a. The control circuit C is comprised of a power supply 20 which supply a desired voltage (or current) and a switch 21.
Furthermore, conductive electrode films 5c and 6c are formed on the side surfaces of the holder 8, and these conductive electrode films 5c and 6c are respectively electrically connected to the electrode films 5 and 6. The material of these conductive electrode films 5c and 6c is the same as that of the electrode films 5 and 6. The holder 8 has a sharpened holder tip end 8a, and the holder tip end 8a is positioned near the surface of a thermal recording medium 22.
The operation of this heat emitting probe 19 will be described below.
When the switch 21 is turned on, the voltage of the power supply 20 is applied to the holder 8 via the conductive electrode films 5c and 6c. Since the holder 8 of the AFM cantilever 2 is formed from a silicon semiconductor and has a fairly large electrical resistance, the holder 8 functions as a heat emitting body. As the holder 8 emits heat, the holder tip end 8a becomes a heating point.
Since the holder tip end 8a is located near the surface of the thermal recording medium 22, the portion of the thermal recording medium 22 that directly faces the holder tip end 8a is melted by heating. As a result, a hole 23 is formed. As the heat emitting probe 19 is appropriately run to scan by a separately installed driving device, holes 23 are intermittently formed by melting. Then, information is recorded on the thermal recording medium by the on-off formation of these numerous holes 23.
In such fusion type holes 23, as the hole diameter D is reduced, the recording density of the thermal recording medium increases. In other words, since the recording density must be considered in terms of a two-dimensional plane, the recording density is inversely proportional to D2. Meanwhile, the hole diameter D depends on the curvature radius of the holder tip end 8a. 
Since the holder 8 is manufactured using semiconductor techniques, it is extremely difficult to reduce the curvature radius of the holder tip end 8a to a value that is less than 10 nm. Since the hole diameter D is larger than this curvature radius, it is an extremely difficult task to control the hole diameter to a value of several tens of nm (nanometer) or less. Accordingly, the recording density of conventional thermal recording media that can be achieved by means of a heat emitting holder utilizing an AFM cantilever has limitations.
Thus, in the past, problems exist not only in regard to the input and output of thermal recording media, but also in regard to thermal measurements of general sample surfaces on the nano-scale. Conventionally, there has been no means for measuring the temperature distribution of the sample surface on the nano-scale. Nor has there been any means in the past for measuring the thermal conductivity distribution of sample surfaces on the nano-scale. However, such thermal measurement sensors are indispensable for the effective development of nano-science.